I think Octavarium was the last album from DT that I dug. I agree with the others, for some reason, the later stuff just did not resonate with me at all.
With Rush, for me, it's been a production thing more than a writing thing. Like, while I don't LOVE all of Hold Your Fire thru Roll The Bones, there are some killer songs and good writing on all of those albums, but I don't enjoy LISTENING to them because of their production. They remedied that with Counterparts, IMO.
Same with Vapor Trails. There is some interesting and good writing on that album, but the "brick wall limiting" killed that album for me.
Clockwork Angels was a GREAT album IMO, and I don't know of another band who was around that long, who ended their recording career with an album THAT good.